Previous studies have indicated that the covalent binding of acetaldehyde to proteins may be responsible for the hepatotoxicity of ethanol. These proposed studies will continue to explore this possibility and, in this regard, the following hypothesis has been formulated: During ethanol oxidation in the liver, acetaldehyde forms stable adducts via binding to "reactive" lysines of preferential target proteins, resulting in selective functional impairment of these proteins and ultimately leading to liver cell injury. the initial objective is to clarify the chemistry of the interaction of acetaldehyde with proteins and to establish the mechanism of stable acetaldehyde-protein adduct formation. This information will be used to prepare appropriate antigens to produce and characterize antibodies that recognize relevant non-reduced stable adducts. These antibodies will then be used to develop a reliable assay for detecting acetaldehyde-protein adducts in the liver and other organs in rats chronically consuming ethanol. The second aim will investigate whether lipid peroxide-derived aldehydes also form stable adducts with hepatic proteins during chronic ethanol administration. In this regard, livers of ethanol-fed rats will be assayed for the presence of malondialdehyde- and 4-hydroxynonenal-protein adducts as well as mixed adducts of acetaldehyde and these peroxide-derived aldehydes. Specific antibodies will again be generated in order to detect these adducts. In the third aim, experiments will determine the time-course levels of stable acetaldehyde and peroxide-derived aldehyde adducts in the livers and other organs of rats consuming ethanol over extended time periods. The lobular and subcellular distribution of these adducts in the liver will be determined, and selective protein targets of adduct formation will be identified. Correlation between the presence and/or distribution of these adducts and ethanol-induced hepatic changes and indices of liver will also be ascertained. A fourth specific aim will be concerned with establishing whether acetaldehyde-tubulin adduct formation results in altered microtubule function (i.e., impaired hepatic protein trafficking) in order to demonstrate a specific functional consequence of adduct formation to a specific target protein (i.e., tubulin) at the cellular level. finally, we intend to test the potential of three separate compounds (aminoguanidine, N-acetylcysteine or penicillamine) in their ability to alter levels of stable acetaldehyde adducts in the liver during chronic ethanol consumption and relate these findings to the ability of these agents to prevent or reduce the extent or severity of ethanol-induced liver injury. Based on these studies, the potential therapeutic role of these agents in the prevention and treatment of alcoholic liver disease can be evaluated. Overall, these proposed studies should provide valuable information concerning the basic molecular mechanisms of alcohol-induced hepatotoxicity.